Scientific Name:  Osmia lignaria

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Mason Bees mate in the spring and the females collect the nectar pollen from flowering trees like the Vine Maple and other flowering plants.  They live alone and make nests in above ground cavities where they deposit their eggs and the pollen and nectar they have collected.  They plug the holes and then the eggs hatch, feed and hibernate until spring.

For more information about Mason Bees read the article by the Arboretum Foundation’s Bulletin titled  Getting to know Northwest Bees  https://arboretumfoundation.org/?s=mason+bee